Pathfinder: Undead with low Charisma made feasible?

[Mystral]

Hi, everyone.

I am currently playing a Tiefling Witch in a game of pathfinder, to be more specific, in the campaign "way of the wicked". She is rather undead themed, with the archetype Gravewalker. I don't know if there is a way for her to become an undead somewhere along the path, but if there was, it would be really fitting.

Problem is, her attributes aren't really perfect for this.

Str 8
Dex 10
Con 17
Int 20
Wis 13
Cha 9

As you can see, her HP would drop trough the floor if she would become undead. The question I am now proposing is, is there any way to circumvent this, perhaps have her HP be based on Int (would be awesome) or Wis (Would still be good enough)? The GM isn't really into homebrew stuff, so it should be part of the official rules. Sadly, I don't own many pathfinder sources, so I haven't found anything, but if someone knew an Item or Talent or something, or at least a good place to look, it would be greatly appreciated. If there isn't, that's okay too, I guess. :)

[Psyren]

1) You actually don't have to own any PF sources, as all of their crunch is available for free on the PFSRD: http://www.d20pfsrd.com/

2) I'm not sure how to make your hp based off Int or Wis in PF, but a good workaround to get some more hp is via temp HP - for example, working Empowered Maximized Greater False Life (http://www.d20pfsrd.com/magic/all-spells/f/false-life) (a witch spell) into your buff routine.

[Erik Vale]

Agent of the Grave [see the SRD] grants various undead themed benefits that you might like, and the capstone assists with becoming undead. Shadow's don't explicitly loose previous HD/etc so you could always be deliberately be killed by one [and possibly try to angle for lesser shadow race instead somehow for only +1 HD, if he'll let that piece of 3rd party through]. This assumes that incorporality would be enough to make up for Cha to HP for you.

You could get someone to make you a permanent Cha boosting item [possibly as a tattoo, [however I'll let you figure out how to get that as a incorporial undead, but I think some sort of polymorph may do] to free up a item slot.]